This invention relates to a magneto generator for an internal combustion engine and more particularly to an improved and simplified manner of forming such a construction and attaching it to the crankshaft of the associated engine.
Conventionally with a wide variety of types of engines, particularly but not limited to those of the small displacement type, a projecting end of the crankshaft has attached to it a flywheel, a starter mechanism and magneto generator assembly. These mechanisms comprise a number of component parts that are connected to each other by a plurality of different types of fasteners. In addition, it is also the common practice to provide a protective coating over the permanent magnets of the magneto generator to protect them. These structures have a number of defects, which may be best understood by reference to FIG. 1 which is a figure showing a conventional prior art type of construction.
An associated engine has a crankshaft, indicated generally by the reference numeral 11, which protrudes through an end face of the associated crankcase in which the crankshaft 11 is journalled in a well known manner. A flywheel magneto starter assembly, indicated generally by the reference numeral 12, is affixed to the crankshaft 11 in a manner that will be described. This flywheel magneto starter assembly 12 includes a number of components including a mounting boss member, indicated generally by the reference numeral 13 and which has a flange portion 14 that is generally cylindrical in shape. The flange portion 14 is integrally formed with a cylindrical sleeve part 15 and which has an internal bore 16 that is received over a tapered end of the crankshaft 11. A key 17 is positioned in a key groove 18 formed in the crankshaft 11 and in a slot formed in the sleeve bore 16 so as to non-rotatably affix the mounting boss member 13 to the crankshaft 11.
A flywheel magneto member 19 is affixed, in a manner to be described, to the mounting boss member 13 and cooperates with a stator 21 that is fixed to the engine body. The flywheel magneto assembly 12 generates electrical power for, among other things, the ignition of the associated engine.
The flywheel magneto member 19 has a generally cup-shape comprised of a cylindrical flange 22 and an end wall 23. Carried on the inner periphery of the cylindrical portion 22 are a plurality of permanent magnets 24 that cooperate with the stator 21 so as to generate an electrical current therethrough on rotation of the flywheel magneto assembly 12 with the crankshaft 11.
The flywheel magneto member 19 is affixed to the mounting boss member 13 by means of a plurality of rivets, indicated by the reference numeral 25. These rivets 25 have headed portions that are disposed on one side of the end wall 23 and conical portions that are received in correspondingly machined openings 26 formed in the mounting boss member 13. The conical portions 26 are required in order to clear a one-way clutch assembly, indicated generally by the reference numeral 27 which is associated with a starter gear 28 that is journalled on the crankshaft 11 and has teeth on its outer periphery. A starter motor is engaged with these teeth for rotating the starter gear 28.
The one-way clutch 27 includes an inner race that is formed by a hub 29 of the starter gear 28 and which drives a plurality of sprags 31 and retainers 32 for driving an outer race 33. The outer race 33 has tapped openings that receive threaded fasteners 34. The threaded fasteners 34 are socket headed screws and pass through enlarged openings in the flywheel end wall 23 so as to affix the outer race 33 to the mounting boss member 13.
Finally, spacers 35 are positioned internally of the permanent magnets 28 to space them at a fixed distance from the end wall 23 and a protective covering 36 covers the surfaces of the permanent magnets 24 so as to protect them. The protective casing 36 is made from a non-magnetic material such as stainless steel and is adhesively bonded to the permanent magnets 24.
It should be readily apparent from the foregoing description that the prior art type construction is rather time consuming to manufacturer and assemble. The problems associated with the use of the fastening rivets 25 have already been touched upon. In addition, the use of the separate threaded fasteners for securing the hub portion 13 to the one-way clutch outer race 33 adds to the number of fasteners in the area and thus, weakens the overall assembly. The use of the relatively large number of fasteners and the associated holes through which they pass requires thickening of these members which adds weight in an area where it aids little to the flywheel effect. It would be better to have the added material on the outer periphery where the effect would be greater.
Furthermore, the adhesive bonding of the protective cover 36 to the permanent magnets 24 gives rise to not only a messy operation but also requires time for setting before the assembly can be completed and used.
It, therefore, a principal object to this invention to provide an improved flywheel magneto for an internal combustion engine.
It is a further object to this invention to provide an improved, simplified lower cost and better performing flywheel magneto that offsets the disadvantages noted.
A first feature of the invention is embodied in a flywheel rotor of a magneto generator for an internal combustion engine for rotating together with a crankshaft of the engine. The flywheel rotor comprises a mounting member having a sleeve portion adapted to be nonrotatably secured on the crankshaft and a flange portion formed integrally with the sleeve portion. The flange portion is generally in the shape of a disc. An engine starter component is disposed on one side of the flange portion and a flywheel member generally in the shape of a cup is disposed on the other side of the flange portion. A plurality of circumferentially spaced permanent magnets are affixed on the inner surface of the flywheel member. A plurality of threaded fasteners, each having portions extending axially through each of the flange portion, the engine starter component and the flywheel forming the sole connection between the mounting member, the engine starter component and the flywheel member.
Another feature of the invention is also embodied in a flywheel rotor of a magneto generator for an internal combustion engine for rotating together with a crankshaft of the engine. In accordance with this feature, the flywheel rotor also comprises a mounting member having a sleeve portion adapted to be nonrotatably secured on the crankshaft and a flange portion formed integrally with the sleeve portion. The flange portion is generally in the shape of a disc. An engine starter component is disposed on one side of the flange portion and a flywheel member generally in the shape of a cup is disposed on the other side of the flange portion. A plurality of circumferentially spaced permanent magnets are affixed on the inner surface of the flywheel member. A permanent magnet protection casing generally in the shape of a cup is received within the flywheel member in close contact with inner surfaces of the permanent magnets. A plurality of fasteners affix the engine starter component, the flywheel, the boss member and the permanent magnet protection casing to each other.